PRB: Must Open MDB on Read-Only Media with adShareDenyWrite (195475)

SYMPTOMS

Opening the connection on a read-only Microsoft Access Database (.mdb file on a CD-ROM, a floppy disk that is write protected, or a hard disk that is read-only to the user, and so forth) with the following code causes an error to occur. The following code opens a connection on a Microsoft Access database file on a CD-ROM:

   Dim con as new ADODB.Connection
   con.Provider = "Microsoft.Jet.Oledb.3.51"
   con.Open "Data Source=E:\testdb.mdb"

It causes the following error:

The Microsoft Jet database engine cannot open the file E:\testdb.mdb. It is already opened exclusively by another user, or you need permission to view its data.

CAUSE

The Jet OLEDB provider opens databases, by default, in Read/Write mode. Jet requires the creation of a locking file (.ldb file) in order to open a database file in shared access mode. If you request shared access mode, Jet attempts to create the locking file, which fails on read-only media. If you open a database using exclusive mode, Jet does not need to create the locking file.

RESOLUTION

Open the database in read-only and exclusive mode. You can do this by setting the Mode property of the connection object to adShareDenyWrite.

The following code opens a connection on a read-only Microsoft Access database:

   Dim con as new ADODB.Connection
   con.Provider = "Microsoft.Jet.Oledb.3.51"
   con.Mode = adShareDenyWrite
   con.Open "Data Source=E:\testdb.mdb"

REFERENCES

The following Microsoft Knowledge Base article describes the same problem and a resolution when using Data Access Object (DAO):

191737 PRB: DAO MDB on Read-Only Media Must Be Opened Exclusively

Microsoft Developer Network Library, Visual Studio 6.0; search on:

Microsoft Data Access SDK